Log data collection system, terminal device, and log data collection method

ABSTRACT

A log data collection system includes a terminal device accumulating log data; and a collection device collecting the log data from the terminal device through a network, wherein the terminal device includes transmission determination unit which determines a timing of transmitting the log data to the collection device, within a permissible transmission period, being a time span in which transmission of the log data is permitted, based on a state of the terminal device, a state of the network, and a remaining time of the permissible transmission period.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a national stage application of InternationalApplication No. PCT/JP2014/004762 entitled “LOG DATA COLLECTION SYSTEM,TERMINAL DEVICE, AND LOG DATA COLLECTION METHOD,” filed on Sep. 17,2014, which claims the benefit of the priority of Japanese PatentApplication No. 2014-004920 filed on Jan. 15, 2014, the disclosures ofeach of which are hereby incorporated by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a log data collection system, aterminal device, a log data collection method, and a program, and moreparticularly relates to a log data collection system, a terminal device,a log data collection method, and a program, for collecting log dataaccumulated in a terminal device.

BACKGROUND ART

A log data collection system is a system aggregating log data, withrespect to a plurality of terminal devices, into a log collectionserver, by periodically transmitting log data accumulated in a terminaldevice, such as positional information and a usage history of anapplication, from the terminal device to the log collection server.Examples of technologies related to a log data collection system aredisclosed in PTL 1, 2, and 3.

In PTL 1, components corresponding to the terminal device and the logcollection server are respectively described by the names of an agentterminal device and an administrative server device. In a log datacollection system presented in PTL 1, an administrative server devicedelivers a log collection schedule to an agent terminal device. Then,the agent terminal device transmits obtained log data to theadministrative server device at a time specified in the delivered logcollection schedule.

In PTL 2, components corresponding to the terminal device and the logcollection server are respectively described by the names of adistributed device and a central device. An object of a log datacollection system presented in PTL 2 is to collect log data with highfrequency, when some anomaly occurs in a distributed device.Furthermore, loads on a distributed device and a central device areperiodically monitored, and collected at a time of a low load.

In PTL 3, components corresponding to the terminal device and the logcollection server are respectively described by the names of a clientand a server. Further, machine information collection is targeted asprocessing corresponding to log collection. A machine informationcollection system presented in PTL 3 includes a method of collectingmachine information, in accordance with a schedule delivered from aserver to a client, and a method of starting machine informationcollection only at a time of a low client machine load. Thus, it isrealized that a machine load and a network load, accompanying machineinformation collection, are distributed.

CITATION LIST Patent Literature

PTL 1: Japanese Unexamined Patent Application Publication No.2008-217118

PTL 2: Japanese Unexamined Patent Application Publication No.2002-259236

PTL 3: Japanese Unexamined Patent Application Publication No.2001-306511

SUMMARY OF INVENTION Technical Problem

When periodically collecting log data composed of positionalinformation, an application usage history, and the like, through awireless network such as wideband code division multiple access (W-CDMA)and long term evolution (LTE), there is a problem that network trafficgenerated in log data collection may cause occurrence of congestion.

Occurrence of congestion accompanying log data transmission hasfollowing causes.

(1) Effect of background traffic (communication traffic unrelated to logdata collection): A total amount of background traffic and log datacollection traffic by log data collection represents an entire amount ofcommunication traffic. Therefore, even when a proportion of log datacollection traffic in communication traffic is low,transmission/reception of log data may trigger occurrence of congestion,depending on a background traffic situation.

FIG. 9 is a diagram illustrating an example of background traffic andlog data collection traffic. The example illustrates a situation thatbackground traffic TR1 is maximum around 12:00 and log data collectiontraffic alone is nearly constant throughout 24 hours. In such asituation, entire communication traffic TR2 increases or decreases withfluctuation of the background traffic TR1, and therefore congestion CNmay occur at a peak time.

(2) Effect of wireless state transition of a terminal device: Dependingon a state of a terminal device at a timing of transmitting log datafrom the terminal device, excessive communication traffic may occur.

In a wireless network such as W-CDMA and LTE, states such as an activestate and an idle state exist between a terminal device and a basestation (specific state names and a number of states vary in accordancewith wireless network standard). Typically, data transmission/receptionis performed in the active state, and the idle state is used in othersituations to suppress consumption of a wireless resource and power.

Consequently, depending on a wireless state RFST when attempting to sendlog data from a terminal device to a server, following differences of(A) and (B) occur (refer to FIG. 10).

(A) When a terminal device is in the idle state: Log data aretransmitted after transitioning from the idle state to the active state(ST). Communication traffic by transmission/reception of a controlsignal required for the state transition ST is generated.(B) When the terminal device is in the active state: Log data aretransmitted from the terminal device to the server without accompanyingstate transition.

Therefore, when log data are transmitted without considering thewireless state RFST of the terminal device, in a case of the state (A),excessive communication traffic may be generated.

In a method of transmitting log data only when a terminal device is in agood state, as described in PTL 2 and 3, when a high load state in anetwork or a terminal device continues, log data transmission isrepeatedly put on hold. Consequently, delay in log data transmission isgenerated, and log data cannot be collected at a timing expected by anapplication using the log data. Therefore, the problem described abovecannot be solved.

The present invention is made to solve such a problem, and an objectthereof is to provide a log data collection system, a terminal device, alog data collection method, and a program, providing collection of logdata within a transmission time limit, while leveling out a network loadaccompanying the collection.

Solution to Problem

A log data collection system according to a first aspect of theinvention includes:

a terminal device accumulating log data; and

a collection device collecting the log data from the terminal devicethrough a network, wherein

the terminal device includes transmission determination unit whichdetermines a timing of transmitting the log data to the collectiondevice, within a permissible transmission period, being a time span inwhich transmission of the log data is permitted, based on a state of theterminal device, a state of the network, and a remaining time of thepermissible transmission period.

A terminal device according to a second aspect of the present inventionincludes:

a storage unit storing log data and a permissible transmission period,being a time span in which transmission of the log data is permitted;and

a transmission determination unit determining a timing of transmittingthe log data to a collection device connected through the network,within the permissible transmission period, based on an own state, astate of the network, and a remaining time of the permissibletransmission period.

A log data collection method according to a third aspect of the presentinvention

is a log data collection method for collecting log data by use of aterminal device accumulating the log data and a collection deviceconnected to the terminal device through a network, wherein,

the method includes, by the terminal device,

determining a timing of transmitting the log data, within a permissibletransmission period, being a time span in which transmission of the logdata is permitted, based on a state of the terminal device, a state ofthe network, and a remaining time of the permissible transmissionperiod, and

transmitting the log data to the collection device at the determinedtiming.

A non-transitory computer readable medium storing a program according toa fourth aspect of the present invention causes a computer to perform:

transmission determination processing of determining a timing oftransmitting log data, within a permissible transmission period, being atime span in which transmission of the log data, accumulated locally, ispermitted, based on an own state, a state of the network, and aremaining time of the permissible transmission period; and

transmission processing of transmitting the log data to a collectiondevice connected through the network at the determined timing.

Advantageous Effects of Invention

The present invention is able to provide a log data collection system, aterminal device, a log data collection method, and a program, forproviding collection of log data within a transmission time limit, whileleveling out a network load accompanying the collection.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating an overall configuration of a logdata collection system according to an exemplary embodiment 1 of thepresent invention.

FIG. 2 is a flowchart illustrating a flow of a log data collectionmethod according to the exemplary embodiment 1 of the present invention.

FIG. 3 is a block diagram illustrating a configuration of a log datacollection system 1 according to an exemplary embodiment 2 of thepresent invention.

FIG. 4 is a diagram illustrating an example of a log collection scheduleaccording to the exemplary embodiment 2 of the present invention.

FIG. 5 is a flowchart illustrating a flow of generation processing ofthe log collection schedule according to the exemplary embodiment 2 ofthe present invention.

FIG. 6 is a diagram illustrating an example of a calculation process ofa permissible log transmission count according to the exemplaryembodiment 2 of the present invention.

FIG. 7 is a flowchart illustrating a flow of determination processing ofa log transmission timing according to the exemplary embodiment 2 of thepresent invention.

FIG. 8 is a diagram illustrating an example of atransmission-determination-score threshold value function according tothe exemplary embodiment 2 of the present invention.

FIG. 9 is a diagram illustrating an example of background traffic andlog data collection traffic.

FIG. 10 is a diagram illustrating a relation between a state of aterminal device and state transition.

FIG. 11 is a block diagram illustrating an overall configuration of alog data collection system according to an exemplary embodiment 3 of thepresent invention.

DESCRIPTION OF EMBODIMENTS

Specific exemplary embodiments applying the present invention will bedescribed in detail below with reference to the drawings. In therespective drawings, a same reference sign is given to a same component,and overlapping description is omitted as appropriate, for clarificationof description.

Exemplary Embodiment 1

FIG. 1 is a block diagram illustrating an overall configuration of a logdata collection system 1000 according to an exemplary embodiment 1 ofthe present invention. The log data collection system 1000 includes aterminal device 200 accumulating log data, and a collection device 100collecting log data from the terminal device 200 through a network N.

The terminal device 200 includes at least a storage unit 210 and atransmission determination unit 220. The storage unit 210 stores logdata 2101 and a permissible transmission period 2102. The log data 2101includes positional information of the terminal device 200, an operationhistory by a user of the terminal device 200, and a state of anapplication. The permissible transmission period 2102 is a time span inwhich transmission of the log data 2101 is permitted. In other words,the permissible transmission period 2102 is a time span defined by astart time and a finish time. The permissible transmission period 2102may be specified by either of a collector of the log data 2101 and auser. Further, the permissible transmission period 2102 may bedetermined based on a communication traffic history of the network N.Further, the communication traffic history of the network N refers to,for example, the aforementioned communication traffic, and is a totalamount of the background traffic and the log data collection traffic,described above, or includes at least the background traffic.

The transmission determination unit 220 is an example of a transmissiondetermination unit, and determines a timing of transmitting the log data2101 to the collection device 100, within the permissible transmissionperiod 2102, based on a state of the terminal device 200, a state of thenetwork N, and a remaining time of the permissible transmission period2102. The state of the terminal device 200 includes, for example, a typeof a connection line through which the terminal device 200 is connectedto the network N at a present time, and a state of establishment of aconnection with the network N. The state of the network N includes, forexample, communication traffic at the present time. The remaining timeof the permissible transmission period 2102 represents a remaining timefrom the present time to a finish time.

FIG. 2 is a flowchart illustrating a flow of a log data collectionmethod according to the exemplary embodiment 1 of the present invention.First, the terminal device 200 appropriately accumulates the log data2101 in the storage unit 210 during normal operation (S101). Next, theterminal device 200 refers to the storage unit 210 to determine whetheror not a present time is within the permissible transmission period 2102(S102). The terminal device 200 returns to Step S101 when the presenttime exists out of the permissible transmission period, and proceeds toStep S103 when the present time exists within the permissibletransmission period.

Next, the transmission determination unit 220 determines a transmissiontiming (S103). Specifically, the transmission determination unit 220determines a timing of transmitting the log data 2101 to the collectiondevice 100, based on a state of the terminal device 200, a state of thenetwork N, and a remaining time of the permissible transmission period2102. Subsequently, the terminal device 200 transmits the log data 2101to the collection device 100 at the determined timing.

Thus, the exemplary embodiment 1 of the present invention is able toprovide collection of log data within a transmission time limit, whileleveling out a network load accompanying the collection. The reason isthat, first, a transmission timing of log data is determined within apermissible transmission period in which transmission of the log data ispermitted based on a communication traffic history of the network N. Inother words, a permissible transmission period, being a theoreticallyproper transmission timing with a certain range (a start time and afinish time), is used in consideration of a past network load(communication traffic). Then, when the log data is actuallytransmitted, a fine adjustment of the proper timing, depending on asituation at the time, is required, and therefore a timing under a lowerload may be determined, in consideration of a state of the terminaldevice 200 and a state of the network N, at a certain point within thepermissible transmission period. There is a concern that, by simplyconsidering a state as of transmission, transmission of the log data maycontinue to be deferred as is the case with PTL 2 and the like, andtherefore, by ensuring determination of the transmission timing withinthe permissible transmission period, the transmission time limit can bereliably observed.

Exemplary Embodiment 2

An exemplary embodiment 2 of the present invention is an applicationexample of the exemplary embodiment 1 described above. Specifically, itis desirable that, in the permissible transmission period, thetransmission determination unit determines a timing of transmitting thelog data to the collection device, by giving higher priority tocommunication of data other than the log data, through the network, as apresent time is closer to a start time of the permissible transmissionperiod, and giving higher priority to transmission of the log data tothe collection device, as the present time is closer to a finish time ofthe permissible transmission period. Thus, log data are transmittedearly when there is a margin for a network load, and, by contrast, inthe event that a high network load continues, transmission of log datais given higher priority than other communications, and therefore aconstraint of a transmission time limit can be observed in considerationof a load in the network and the like.

Further, FIG. 3 is a block diagram illustrating a configuration of a logdata collection system 1 according to the exemplary embodiment 2 of thepresent invention. The log data collection system 1 includes one logcollection server 10 and terminal devices 20, . . . , 2 n. The logcollection server 10 and the terminal devices 20, . . . , 2 n are ableto communicate with each other through a network N. The log datacollection system 1 is an example of the aforementioned log datacollection system 1000, the log collection server 10 is an example ofthe aforementioned collection device 100, and the terminal device 20 andthe like are examples of the aforementioned terminal device 200.

The log collection server 10 includes a schedule generation unit 11, aschedule transmission unit 12, a log collection unit 13, and a storagedevice 14. The schedule generation unit 11 generates a log collectionschedule with respect to each terminal device. The schedule generationunit 11 creates a log collection schedule for each terminal device,being a log collection target, based on, for example, a schedulegeneration operation by a system administrator. The log collectionschedule includes the aforementioned permissible transmission period2102. A generation method of the log collection schedule will bedescribed later. The schedule transmission unit 12 transmits a logcollection schedule, generated for each terminal device, to acorresponding terminal device. The log collection unit 13 receives logdata transmitted from each terminal device, and stores the data into thestorage device 14. The storage device 14 stores log data 141 received bythe log collection unit 13.

The terminal device 20 includes a storage device 21, a log accumulationunit 22, a schedule reception unit 23, a transmission determination unit24, and a log transmission unit 25. The storage device 21 stores logdata 211, a log collection schedule 212, a transmission determinationscore 213, a transmission-determination-score threshold value function214, and a transmission-determination-score threshold value 215. The logdata 211 is equivalent to the aforementioned log data 2101. The logcollection schedule 212 is generated for the terminal device 20 andtransmitted, by the log collection server 10. The transmissiondetermination score 213 is an example of an index value indicating adegree of suitability for transmission of log data at a present time.The transmission-determination-score threshold value 215 is an exampleof a threshold value for permitting transmission of log data at thepresent time. The transmission-determination-score threshold valuefunction 214 is a predetermined function for calculating thetransmission-determination-score threshold value 215, based on a presenttime.

The log accumulation unit 22 stores various data acquired on theterminal device 20 into the storage device 21 as the log data 211. Theschedule reception unit 23 receives a log collection scheduletransmitted from the log collection server 10, and stores the scheduleinto the storage device 21 as the log collection schedule 212. Thetransmission determination unit 24 determines a timing of transmittingthe log data 211, stored in the storage device 21, to the log collectionserver 10. A determination method of a timing of transmitting log datawill be described later. The log transmission unit 25 transmits theaccumulated log data 211, at a timing determined by the transmissiondetermination unit 24, to the log collection server 10.

FIG. 4 is a diagram illustrating an example of a log collection scheduleaccording to the exemplary embodiment 2 of the present invention. A logcollection schedule with respect to a terminal is represented as apermissible transmission period (a pair of a start time and a finishtime), appearing periodically. FIG. 4 illustrates that permissibletransmission periods P11 and P12 are set for a terminal 1, permissibletransmission periods P21 and P22 for a terminal 2, permissibletransmission periods P31 and P32 for a terminal 3, and permissibletransmission periods P41 and P42 for a terminal 4.

A finish time of a permissible transmission period is particularlyreferred to as a log transmission time limit. In FIG. 4, a finish timeof the permissible transmission period P11 is a log transmission timelimit L11, and a finish time of the permissible transmission period P12is a log transmission time limit L12.

Further, a cycle of a log transmission time limit with respect to aterminal is referred to as a log transmission cycle. In FIG. 4, a periodfrom the log transmission time limit L11 to the log transmission timelimit L12 corresponds to a log transmission cycle LSC at the terminal 1.

The schedule generation unit 11 creates a log collection schedule havinga length matching a log transmission cycle. For example, when the logtransmission cycle is one day (24 hours), a generated log collectionschedule has a length of 24 hours in which a permissible transmissionperiod with respect to each terminal device appears precisely once.Lengths of the log transmission cycle and the log collection schedule donot need to match, and, for example, a permissible transmission periodwith respect to each terminal device may appear three times within 24hours of the log collection schedule. Thus, a permissible transmissionperiod for each terminal can be set more flexibly and easily, comparedwith a case of matching lengths of the log transmission cycle and thelog collection schedule. Further, the schedule generation unit 11 can beconsidered to calculate a permissible transmission period at a terminaldevice, based on a history of a network communication traffic other thancommunication of past log data, that is, background traffic. Further,the schedule generation unit 11 also calculates a plurality ofpermissible transmission periods by dispersing a time span, with respectto each of a plurality of terminal devices. Additionally, the logcollection server 10 may monitor the terminal device 20 and the like todetermine when each terminal device transmits locally-accumulated logdata, and generate a log collection schedule.

An example of a determination method of a log transmission cycle is tosynchronize with a cycle of an action performed by use of collected logdata. For example, for a purpose of collecting a movement history of aterminal device as log data, and performing advertisement delivery basedon the result once a day, a log transmission cycle is synchronized tothe advertisement delivery cycle, being a day. The log transmissioncycle does not need to be fixed, and may be variable.

Next an operation of each configuration will be described.

(1) Log collection server 10: Generation of a log collection schedule

With reference to a flowchart in FIG. 5, procedures in generating of alog collection schedule by the schedule generation unit 11 in the logcollection server 10 will be presented below. In procedures below, atime 0 represents a start time of a log collection schedule and a timeslot represents a time elapsed from the time 0. While an example of alength of a time slot is one second, the length is not necessarilylimited thereto. Further, in generation of a log collection schedule, anupper limit C of total communication traffic is determined in advance. Avalue of the upper limit C corresponds to an upper limit of a totalamount of background traffic and log collection traffic in each timeslot, and an example of a unit thereof is Gbit/sec.

Step S11: The schedule generation unit 11 calculates a predicted valueTr[t] of background traffic with respect to each time slot t within arange of a log transmission schedule (an example of a unit is Gbit/sec).

An example of a background traffic calculation unit is to let an averageof past total traffic measurement values at a time equivalent to eachtime slot t be Tr[t], assuming that a range of the log transmissionschedule is 24 hours.

Step S12: The schedule generation unit 11 calculates a permissible logtransmission count N[t] in each time slot t by the following procedures(S22-1 to S22-3).

S22-1: The schedule generation unit 11 calculates permissible trafficTr_max[t] in each time slot t by use of equation (1) below.

[Math. 1]

Tr_max[t]=C−Tr[t]  equation (1)

It is assumed that Tr_max[t]=0 if Tr_max[t]<0.

S22-2: The schedule generation unit 11 calculates a total value, TrSum,of Tr_max[t] with respect to the entire time slots, by use of equation(2) below.

[Math. 2]

TrSum=ΣTr_max[t]  equation (2)

Then, by use of TrSum, the schedule generation unit 11 calculates a logtransmission probability P[t] in each time slot t, by use of equation(3) below.

[Math. 3]

P[t]=Tr_max[t]/ΣTrmax[t]  equation (3)

S22-3: The schedule generation unit 11 calculates a permissible logtransmission count, with respect to a number of terminal devices n andeach time slot t, by use of equation (4) below.

[Math. 4]

N[t]=n×P[t]  equation (4)

N[t] is set to an integer by any one of round-up, round-down, andround-off unit. Additionally, the schedule generation unit 11 may make acorrection so that a total of N[t] with respect to the entire time slotsmatches the number of terminal devices n.

FIG. 6 illustrates an example of a calculation process of thepermissible log transmission count N[t]. In this example, there are atotal of six time slots, being t=0 to 5, and the number of terminaldevices n =10. In Step S22-1, it is assumed that the calculation resultof the permissible traffic Tr_max[t] is Tr_max[0]=50, Tr_max[1]=40,Tr_max[2]=20, . . . as indicated in the table. Consequently, the totalvalue, TrSum, of Tr_max[t] with respect to the entire time slots can becalculated by use of equation (5) below.

[Math. 5]

TrSum=ΣTr_max[t]=200  equation (5)

Consequently, in Step S22-2, P[0]=50/200=0.25, P[1]=40/200=0.2,P[2]=20/200=0.1, . . . are obtained. Furthermore, by use of the resultand n=10, in Step S22-3, N[0]=10×0.25=2 (dropping the fractionalportion), N[1]=10×0.2=2, N[2]=10×0.1=1, . . . are obtained as a result.Additionally, N[5]=3 is obtained by adding a correction of rounding upthe result of N[5] so that a total value of N[t] matches equation (6)below.

[Math. 6]

ΣN[t]=n=10¹⁸  equation (6)

Step S13: The schedule generation unit 11 determines a log transmissiontime limit with respect to each terminal device so as to satisfy thepermissible log transmission count N[t], being the calculation result ofStep S12.

An example of a determination method of the log transmission time limitis to allocate an earlier time slot in ascending order of numberassigned to each terminal device in advance.

With reference to FIG. 6 once again, an example of allocation of a logtransmission time limit to a terminal device will be presented. In thisexample, 10 terminal devices are respectively assigned with numbers D1,D2, . . . , D10, and an earlier time slot is allocated in ascendingorder of the number. Consequently, each terminal device is allocated inaccordance with a permissible log transmission count, being the resultof Step S12, such as D1 and D2 to a time slot t=1, D3 and D4 to a timeslot t=2.

Step S14: The schedule generation unit 11 determines a permissibletransmission period with respect to each of the terminal devices 20 to 2n under the log collection server 10, based on the log transmission timelimit determined in Step S13.

An example of a determination method of the permissible transmissionperiod is to calculate a length of the permissible transmission periodby multiplying a log transmission cycle by a constant value. Forexample, assuming that a log transmission cycle is 48 time slots and acoefficient is 0.1, a length of the permissible transmission period isobtained as 48×0.1=4 (time slots, dropping the fractional portion). Inthis case, assuming that a log transmission time limit with respect to aterminal device is the time slot t=10, the permissible transmissionperiod is obtained as a range from the time slot 7 to the time slot 10.

(2) Log Collection Server 10: Transmission of a Log Collection Schedule

The schedule transmission unit 12 transmits a log collection schedulegenerated in (1) to each terminal device. As a delivery method of a logcollection schedule, each terminal device may periodically acquire a logcollection schedule from the log collection server 20, in addition to amethod of transmission from the log collection server 20 to the terminaldevices 20 to 2 n.

(3) Terminal Device 20: Log Accumulation

Triggered by an event such as an application launch on the own terminaldevice and acquisition of positional information, the log accumulationunit 22 accumulates contents of the event as the log data 211, in thestorage device 21 included in the terminal device.

An example of an event is measurement of a present position at regularintervals by use of a global positioning system (GPS) or the like. Inthis case, a set of a measurement time and positional information beinga measurement result becomes log data. Another example of an event isspecifying a user operation on a smart phone, such as an applicationlaunch and a screen transition, as an event, and a set of a time, anapplication name, and an operation name as log data. Note that logaccumulation processing in (3) is independent of Log collection schedulegeneration processing in (1) and Log collection schedule transmissionprocessing in (2), and there is no restriction on a chronologicalrelation.

(4) Terminal Device 20: Determination of a Log Transmission Timing

The transmission determination unit 24 determines a timing oftransmitting log data, accumulated in the terminal, within a range ofthe permissible transmission period determined in (1), to the logaccumulation server. By performing the processing below at regularintervals (such as every second), whether or not to transmit log data atthe time is determined.

With reference to a flowchart in FIG. 7, determination procedures of alog transmission timing will be presented below.

Step S21: The transmission determination unit 24 checks whether apresent time t is within a range of a permissible transmission periodset to the terminal device. Specifically, the transmission determinationunit 24 determines whether or not a present time t is within a range ofa permissible transmission period, with reference to the log collectionschedule 212 stored in the storage device 21. The transmissiondetermination unit 24 proceeds to Step S22 when the time is within thepermissible transmission period, and ends the processing otherwise.

Step S22: The transmission determination unit 24 checks whether log dataare already transmitted within the present permissible transmissionperiod. The transmission determination unit 24 proceeds to Step S23 whenthe data are not yet transmitted, and ends the processing when the dataare already transmitted.

Step S23: The transmission determination unit 24 calculates atransmission determination score S[t] at a present time t. Thetransmission determination score S[t] is a numerical value quantifying adegree of suitability for data transmission at the time t, and iscalculated from states of the terminal device and the network. In otherwords, the transmission determination unit 24 includes an index valuecalculation unit which calculates an index value indicating a degree ofsuitability for transmission of log data at a present time, based on astate of the terminal device 200 and a state of the network N.

An example of a calculation method of the transmission determinationscore S[t] will be presented below. In a case that a terminal device isconnected to Wi-Fi, traffic to a mobile phone network is not generated,and therefore a higher score is assigned than a case that the device isconnected to a mobile phone network. This can be considered that, in acase that communication through a plurality of lines is available, whenthe device is connected to a line (such as Wi-Fi) through whichcommunication of the device is preferentially performed compared withanother line, stable and, high-speed communication is available, andtherefore a higher score is assigned.

Further, another round of connection establishment processing is notnecessary within a certain period after the last communication (somedata transmission/reception) by the terminal device, and therefore ascore higher than that for other cases is assigned. This can be viewedas a state in which the terminal device 200 is ready for datacommunication.

Further, when the terminal device is currently in (some data)communication, the communication may decrease a transfer speed ofanother communication, and therefore a score lower than that for othercases is assigned.

An example of a specific calculation method of S[t] is as follows.

When a terminal is in Wi-Fi connection, add “10” to S[t].

When a time elapsed since the last communication by the terminal is lessthan or equal to five seconds, add “3” to S[t].

When the terminal is currently not in communication, add “1” to S[t].

Further, when the terminal device is able to acquire a networkcongestion state from a connected base station or the like, the statemay be added to the transmission determination score. For example, alower score may be assigned as the network congestion is heavier.

When log data are periodically collected, a battery at a terminal isconsumed at every log data transmission, and therefore, in addition tothe aforementioned problem, there is another problem that a batteryusage time decreases. For example, as described in Technical Problem,when a terminal device is in the idle state, log data are transmittedafter transition from the idle state to the active state (ST). At thistime, although not being part of the log data transmission processing,battery consumption accompanying the state transition ST occurs.

By contrast, in calculation of the transmission determination score S[t]according to the exemplary embodiment of the present invention, when theterminal device 20 is in a state ready for data communication, a higherscore is calculated. Therefore, the active state is more preferable fordetermining a transmission timing than the idle state in which aconnection is not established, and thus battery consumption can besuppressed.

Step S24: The transmission determination unit 24 calculates value of atransmission-determination-score threshold function T[t] at a presenttime t. The transmission-determination-score threshold value functionT[t] is a function having a value greater than 0 at a start time, beingcalculated to be less than a previous value as time elapses (a value oft becomes greater) in a permissible transmission period, and having avalue T[t]=0 at a log transmission time limit. In other words, it isassumed that a value near a finish time is equivalent to or less than avalue near a start time within a permissible transmission period. Thatis, the transmission-determination-score threshold value function T[t]can be considered as a function decreasing a value in response toincrease of a time t. It is preferable that thetransmission-determination-score threshold value function T[t] is givenfrom outside the log data collection system in advance. Thus, in thisStep S24, a value of the transmission-determination-score thresholdvalue function T[t] at a present time t is calculated.

In other words, the transmission determination unit 24 includes athreshold value calculation unit which calculates a threshold value forpermitting transmission of the log data at a present time. The thresholdvalue calculation unit calculates a threshold value at a present time soas to decrease the threshold value from an initial threshold value at astart time of the permissible transmission period, in response to a timeelapsed from the start time to the present time, and, when the presenttime is a finish time of the permissible transmission period, calculatesthe lowest index value as a threshold value at the present time.Additionally, it is desirable that the threshold value calculation unitperforms calculation by decreasing a threshold value, as a present timeelapses from the start time, at least in a partial time span in thepermissible transmission period. Thus, a fine adjustment of atransmission timing is available.

FIG. 8 illustrates an example of the transmission-determination-scorethreshold value function T[t]. It is assumed that a span between a starttime t0 and a log transmission time limit t2 is set as a permissibletransmission period P. It is further assumed that atransmission-determination-score threshold value STH in a span betweenthe start time t0 and a time t1 is a constant value, thetransmission-determination-score threshold value STH monotonicallydecreases in a span between the time t1 and the log transmission timelimit t2, and the transmission-determination-score threshold value STHbecomes 0 at the log transmission time limit t2. The time t1 may be setat any time at or after t0 and before t2.

Step S25: The transmission determination unit 24 compares value of thetransmission determination score S[t], calculated in Step S23, with thetransmission-determination-score threshold value STH, calculated in StepS24. The transmission determination unit 24 proceeds to Step S26 whenvalued of the transmission determination score S[t] is greater than orequal to the transmission-determination-score threshold value STH, andends the processing otherwise.

Step S26: The transmission determination unit 24 transmits the log data,accumulated in the terminal device, to the log collection server, andends the processing.

Next, a supplementary description will be provided on an effect ofmaintaining or decreasing a transmission-determination-score thresholdvalue T, in response to time increase. As a constraint in determinationof a log transmission timing, log transmission needs to be determined bythe log transmission time limit. Further, in order to solve the problemby the present invention, log transmission needs to be determined at atime under a minimum network load possible.

When there is sufficient time before the log transmission time limit,log transmission can be put on hold until a more preferable condition(that is, with less background traffic and a communication state of theterminal being active) arrives, by setting thetransmission-determination-score threshold value high. By contrast, whenthere is no sufficient time before the log transmission time limit,satisfying the constraint of the log transmission time limit needs to begiven priority.

Consequently, an effect of minimizing a network load within theconstraint of the log transmission time limit may be obtained, bygradually decreasing (or at least maintaining) thetransmission-determination-score threshold value from an initial valueto eventually 0, within the permissible transmission period.

Although the transmission-determination-score threshold value accordingto the present exemplary embodiment is presented in a form in which thevalue is maintained at a constant value up to a certain point, andgradually decreased linearly therefrom, the form is not necessarilylimited thereto. The transmission-determination-score threshold valuefunction T[t] may take another form such as a form of linearlydecreasing values throughout the entire permissible transmission period,and a form of exponentially decreasing values. That is, for example, thefunction may simply decrease values from the start time t0 toward thelog transmission time limit t2, without having the time t1, in theexample in FIG. 8. Any function such as an exponential function may beapplied to the function. Further, when the time t1 is set, the negativeslope may be changed or the function may be changed at the time t1.Further, a plurality of intermediate times corresponding to the time t1may be set. Further, the threshold value may reach 0 before the logtransmission time limit t2, and be set to a constant value therefrom.Further, the function may take discontinuous values between the starttime t0 and the log transmission time limit t2. In this case, thetransmission-determination-score threshold value STH only needs to havea nonzero value at least at the start time t0, and therefrom have avalue equivalent to or less than an immediately preceding value up tot2, as time elapses.

The transmission determination score S[t] and thetransmission-determination-score threshold value T[t] do not need tohave numerical values. For example, they only need to be expressed bylevel values such as A, B, and C, and be index values capable ofdistinguishing at least two levels such as high and low.

(5) Terminal Device 20: Log Transmission (Log Transmission Unit)

When transmission of log, accumulated in the terminal, is determined in(4), the log transmission unit 25 transmits the log data 211,accumulated at that point, to the log collection server 10, and erasesthe log data 211 from the storage device 21. The log may be compressedbefore transmission in order to reduce a data amount to be transmitted.

(6) Log Collection Server 10: Log Collection (Log Collection Unit)

The log collection unit 13 receives log data transmitted from theterminal device 20 in (5), and stores the data into the storage device14 as the log data 141. When the log is received in a compressed state,the log is stored after being decompressed.

An example of an implementation method of the log transmissionprocessing in (5) and the log reception processing in (6) is to operatea hypertext transfer protocol (HTTP) server on the log collection server10, and to transmit log data from the terminal device 20 to the logcollection server 10 in an HTTP POST method.

As described above, the exemplary embodiment of the present invention isable to create a log transmission schedule so as to transmit log datafrom more terminal devices in a time span in which lighter backgroundtraffic is predicted. In addition, a certain range is provided to a logtransmission time from a terminal device, and, transmission may bepreferentially performed when background traffic is light or theterminal device is in an active state. Thus, an effect of leveling out anetwork load accompanying log data collection, and suppressing batteryconsumption at a terminal device, is obtained.

Exemplary Embodiment 3

An exemplary embodiment 3 according to the present invention representsa minimum configuration of a log data collection system according to thepresent invention. FIG. 11 is a block diagram illustrating an overallconfiguration of a log data collection system 3000 according to theexemplary embodiment 3 of the present invention. The log data collectionsystem 3000 includes a terminal device 320 accumulating log data and acollection device 310 collecting log data from the terminal device 320through a network N.

The terminal device 320 includes at least a transmission determinationunit 321. The transmission determination unit 321 determines a timing oftransmitting log data to the collection device 310, within a permissibletransmission period, being a time span in which transmission of the logdata is permitted, based on a state of the terminal device 320, a stateof the network N, and a remaining time of the permissible transmissionperiod.

Thus, the terminal device 320, first, is able to specify a transmissiontiming of log data within a range of a permissible transmission periodhaving a certain time span range. Therefore, the log data collectionsystem 3000 according to the exemplary embodiment 3 of the presentinvention is able to provide log data collection within a transmissiontime limit. Further, when determining a transmission timing of log data,the terminal device 320 takes into consideration a state of the terminaldevice 320, a state of the network N, and a remaining time of thepermissible transmission period, at that point. Therefore, the log datacollection system 3000 according to the exemplary embodiment 3 of thepresent invention is able to level out a network load accompanying thelog data collection.

Another Exemplary Embodiment

Another exemplary embodiment of the present invention may be expressedas follows. A log collection schedule, permitting a certain temporalfluctuation, is created in advance with respect to each terminal device,based on a past measurement result of background traffic, and isdelivered to each terminal device. Each terminal device transmits logdata, accumulated in the terminal device, to a log collection server, inaccordance with the log collection schedule. In order to determine atiming of transmitting log data, each terminal device calculates adegree of suitability for data transmission from states of the terminaldevice and the network, as a log transmission determination score,compares the score with a separately calculated logtransmission-determination-score threshold value, and, when the formeris greater than or equal to the latter, transmits the log data. Bygradually bringing a log transmission-determination-score thresholdvalue close to 0 within a permitted time in the log collection schedule,when there is sufficient time, a situation suitable for datatransmission is selected and log transmission is performed. Thus, bydetermining a transmission timing of log data on the terminal deviceside, within a range permitted on the log collection server side,communication traffic and a load on a terminal device, accompanying logdata collection, can be suppressed, and a temporal fluctuation ofcommunication traffic can be leveled out.

Alternatively, the another exemplary embodiment of the present inventionmay be expressed as follows. In a log data collection systemperiodically collecting log data from a large number of terminaldevices, a log data collection schedule is created, reflecting a pastfluctuation of a network load, and a network load accompanying log datacollection is leveled out by determining a timing of transmitting logdata by each terminal device, based on the log data collection scheduleand a terminal state and a network state during operation.

Furthermore, the another exemplary embodiment of the present inventionmay also be expressed as follows. A log data collection system isprovided, characterized by including a log collection server and atleast one terminal device, wherein the log collection server creates alog transmission schedule assigning a log transmission time limit toeach terminal device so that a total amount of network traffic isleveled out with respect to each terminal device, based on a pastmeasurement result of background traffic, and delivers the result toeach terminal device, and each terminal device transmits log data,accumulated in the terminal device, to the log collection server, withina range observing a log transmission time limit assigned to the terminaldevice, at a timing of a log transmission determination score,calculated in accordance with states of the terminal and the network,being greater than or equal to a separately calculated logtransmission-determination-score threshold value.

The log collection server 10 according to the exemplary embodiment 2 ofthe present invention may be applied to a log collection servercollecting log data accumulated on a smart phone, such as a useroperation history and a sensor measurement result, through a wirelessnetwork. Alternatively, the log collection server 10 may be applied toan information collection server for a sensor network or amachine-to-machine (M2M) network, collecting a measurement result from asensor device through a wireless network.

Furthermore, the present invention is not limited to the aforementionedexemplary embodiments, and it goes without saying that variousmodifications may be made within the scope of the present inventionalready described. For example, although the present invention isdescribed as a hardware configuration in the aforementioned exemplaryembodiments, the present invention is not limited thereto. The presentinvention may provide any processing by causing a central processingunit (CPU) to execute a computer program. In this case, the computerprogram may be stored by use of various types of non-transitorycomputer-readable media and provided to the computer.

A non-transitory computer-readable medium includes various types oftangible storage media. An example of a non-transitory computer-readablemedium includes a magnetic storage medium (such as a flexible disk, amagnetic tape, and a hard disk drive), a magneto-optical storage medium(such as a magneto-optical disk), a compact disk read only memory(CD-ROM), a CD-R, a CD-R/W, a digital versatile disc (DVD), a Blu-ray(registered trademark) Disc (BD), and a semiconductor memory (such as amask ROM, a programmable ROM [PROM], an erasable PROM [EPROM], a flashROM, and a random access memory [RAM]). Further, the computer programmay be provided to the computer by various types of transitorycomputer-readable media. An example of a transitory computer-readablemedium includes an electric signal, an optical signal, and anelectromagnetic wave. A transitory computer-readable medium is capableof providing the program to the computer through a wired communicationchannel, such as an electric cable and an optical fiber, or a wirelesscommunication channel.

The present invention is not limited to the aforementioned exemplaryembodiments, and may be modified as appropriate within the scope of thepresent invention. Furthermore, the aforementioned exemplary embodimentsmay also be described in part or in whole as the following SupplementaryNotes but are not limited thereto.

(Supplementary Note 1)

A log data collection system including:

a terminal device accumulating log data; and

a collection device collecting the log data from the terminal devicethrough a network, wherein

the terminal device includes transmission determination unit whichdetermines a timing of transmitting the log data to the collectiondevice, within a permissible transmission period, being a time span inwhich transmission of the log data is permitted, based on a state of theterminal device, a state of the network, and a remaining time of thepermissible transmission period.

(Supplementary Note 2)

The log data collection system according to Supplementary Note 1,wherein

the transmission determination unit, in the permissible transmissionperiod, determines a timing of transmitting the log data to thecollection device, by giving higher priority to communication of dataother than the log data, through the network, as a present time iscloser to a start time of the permissible transmission period, andgiving higher priority to transmission of the log data to the collectiondevice, as the present time is closer to a finish time of thepermissible transmission period.

(Supplementary Note 3)

The log data collection system according to Supplementary Note 1 or 2,wherein

the transmission determination unit includes:

index value calculation unit which calculates an index value indicatinga degree of suitability for transmission of the log data at a presenttime, based on a state of the terminal device and a state of thenetwork; and

threshold value calculation unit which calculates a threshold value forpermitting transmission of the log data at the present time, theterminal device further includes

log transmission unit which transmits the accumulated log data to thecollection device, when the index value is greater than or equal to thethreshold value, and

the threshold value calculation unit:

calculates the threshold value at the present time so as to, in responseto a time elapsed from a start time of the permissible transmissionperiod to the present time, decrease the threshold value from an initialvalue of the threshold value at the start time; and,

when the present time is a finish time of the permissible transmissionperiod, calculates a lowest value of the index value as the thresholdvalue at the present time.

(Supplementary Note 4)

The log data collection system according to Supplementary Note 3,wherein

the threshold value calculation unit performs calculation by decreasingthe threshold value as the present time elapses from the start time, atleast in a partial time span in the permissible transmission period.

(Supplementary Note 5)

The log data collection system according to any one of claims 1 to 4,wherein

a state of the terminal device includes a type of a connection line,through which the terminal device is connected to the network, and astate of establishment of a connection with the network.

(Supplementary Note 6)

The log data collection system according to any one of SupplementaryNotes 1 to 5, wherein

the permissible transmission period is determined based on acommunication traffic history of the network.

(Supplementary Note 7)

The log data collection system according to any one of

Supplementary Notes 1 to 6, wherein the collection device:

calculates the permissible transmission period at the terminal device,based on a communication traffic history of the network, excluding acommunication traffic related to transmission of the log data in thepast; and

transmits the calculated permissible transmission period to the terminaldevice, and

the terminal device

determines a timing of transmitting the log data to the collectiondevice by the transmission determination unit, based on the permissibletransmission period received from the collection device.

(Supplementary Note 8)

A terminal device including:

storage unit which stores log data and a permissible transmissionperiod, being a time span in which transmission of the log data ispermitted; and

transmission determination unit which determines a timing oftransmitting the log data to a collection device connected through anetwork, within the permissible transmission period, based on an ownstate, a state of the network, and a remaining time of the permissibletransmission period.

(Supplementary Note 9)

A log data collection method for collecting log data, by use of aterminal device accumulating the log data and a collection deviceconnected to the terminal device through a network, the methodincluding, by the terminal device:

determining a timing of transmitting the log data, within a permissibletransmission period, being a time span in which transmission of the logdata is permitted, based on a state of the terminal device, a state ofthe network, and a remaining time of the permissible transmissionperiod; and

transmitting the log data to the collection device at the determinedtiming.

(Supplementary Note 10)

A non-transitory computer-readable medium storing a program causing acomputer to perform:

transmission determination processing of determining a timing oftransmitting log data, within a permissible transmission period, being atime span in which transmission of the log data, accumulated locally, ispermitted, based on an own state, a state of a network, and a remainingtime of the permissible transmission period; and

transmission processing of transmitting the log data to a collectiondevice connected through the network, at the determined timing.

(Supplementary Note 11)

The log data collection system according to any one of SupplementaryNotes 1 to 7 including a terminal device group including the terminaldevice and another terminal device, wherein the collection device:

calculates a plurality of the permissible transmission periods bydispersing a time span for each terminal device included in the terminaldevice group, based on a communication traffic history of the network;and

transmits the calculated permissible transmission periods tocorresponding terminal devices, respectively, and

each terminal device

determines a timing of transmitting the log data to the collectiondevice by the transmission determination unit, based on the permissibletransmission period received from the collection device.

While the present invention has been described above with reference tothe exemplary embodiments, the present invention is not limited to theaforementioned description. Various changes and modifications that canbe understood by those skilled in the art may be made to theconfigurations and details of the present invention, within the scope ofthe present invention.

This application claims priority based on Japanese Patent ApplicationNo. 2014-4920 filed on Jan. 15, 2014, the disclosure of which is herebyincorporated by reference thereto in its entirety.

REFERENCE SIGNS LIST

-   -   1000 Log data collection system    -   100 Collection device    -   200 Terminal device    -   210 Storage unit    -   2101 Log data    -   2102 Permissible transmission period    -   220 Transmission determination unit    -   1 Log data collection system    -   10 Log collection server    -   11 Schedule generation unit    -   12 Schedule transmission unit    -   13 Log collection unit    -   14 Storage device    -   141 Log data    -   20 Terminal device    -   21 Storage device    -   211 Log data    -   212 Log collection schedule    -   213 Transmission determination score    -   214 Transmission-determination-score threshold value function    -   215 Transmission-determination-score threshold value    -   22 Log accumulation unit    -   23 Schedule reception unit    -   24 Transmission determination unit    -   25 Log transmission unit    -   2 n Terminal device    -   N Network    -   LSC Log transmission cycle    -   P11 Permissible transmission period    -   P12 Permissible transmission period    -   P21 Permissible transmission period    -   P22 Permissible transmission period    -   P31 Permissible transmission period    -   P32 Permissible transmission period    -   P41 Permissible transmission period    -   P42 Permissible transmission period    -   L11 Log transmission time limit    -   L12 Log transmission time limit    -   t0 Start time    -   t1 Time    -   t2 Log transmission time limit    -   TR1 Communication traffic (background traffic+log data        collection traffic)    -   TR2 Background traffic    -   CN Congestion    -   TRL Traffic limit    -   RFST Wireless state    -   ST State transition    -   P Permissible transmission period    -   STH Transmission-determination-score threshold value    -   3000 Log data collection system    -   310 Collection device    -   320 Terminal device    -   321 Transmission determination unit

1. A log data collection system comprising: a terminal deviceaccumulating log data; and a collection device collecting the log datafrom the terminal device through a network, wherein the terminal deviceincludes transmission determination unit which determines a timing oftransmitting the log data to the collection device, within a permissibletransmission period, being a time span in which transmission of the logdata is permitted, based on a state of the terminal device, a state ofthe network, and a remaining time of the permissible transmissionperiod.
 2. The log data collection system according to claim 1, whereinthe transmission determination unit, in the permissible transmissionperiod, determines a timing of transmitting the log data to thecollection device, by giving higher priority to communication of dataother than the log data, through the network, as a present time iscloser to a start time of the permissible transmission period, andgiving higher priority to transmission of the log data to the collectiondevice, as the present time is closer to a finish time of thepermissible transmission period.
 3. The log data collection systemaccording to claim 1, wherein the transmission determination unitincludes: index value calculation unit which calculates an index valueindicating a degree of suitability for transmission of the log data at apresent time, based on a state of the terminal device and a state of thenetwork; and threshold value calculation unit which calculates athreshold value for permitting transmission of the log data at thepresent time, the terminal device further includes log transmission unitwhich transmits means for transmitting the accumulated log data to thecollection device, when the index value is greater than or equal to thethreshold value, and the threshold value calculation unit: calculatesthe threshold value at the present time so as to, in response to a timeelapsed from a start time of the permissible transmission period to thepresent time, decrease the threshold value from an initial value of thethreshold value at the start time; and, when the present time is afinish time of the permissible transmission period, calculates a lowestvalue of the index value as the threshold value at the present time. 4.The log data collection system according to claim 3, wherein thethreshold value calculation unit performs calculation by decreasing thethreshold value as the present time elapses from the start time, atleast in a partial time span in the permissible transmission period. 5.The log data collection system according to claim 1, wherein a state ofthe terminal device includes a type of a connection line, through whichthe terminal device is connected to the network, and a state ofestablishment of a connection with the network.
 6. The log datacollection system according to claim 1, wherein the permissibletransmission period is determined based on a communication traffichistory of the network.
 7. The log data collection system according toclaim 1, wherein the collection device: calculates the permissibletransmission period at the terminal device, based on a communicationtraffic history of the network, excluding a communication trafficrelated to transmission of the log data in the past; and transmits thecalculated permissible transmission period to the terminal device, andthe terminal device determines a timing of transmitting the log data tothe collection device by the transmission determination unit, based onthe permissible transmission period received from the collection device.8. A terminal device comprising: storage unit which stores log data anda permissible transmission period, being a time span in whichtransmission of the log data is permitted; and transmissiondetermination unit which determines a timing of transmitting the logdata to a collection device connected through a network, within thepermissible transmission period, based on an own state, a state of thenetwork, and a remaining time of the permissible transmission period. 9.A log data collection method for collecting log data, by use of aterminal device accumulating the log data and a collection deviceconnected to the terminal device through a network, the methodcomprising, by the terminal device: determining a timing of transmittingthe log data, within a permissible transmission period, being a timespan in which transmission of the log data is permitted, based on astate of the terminal device, a state of the network, and a remainingtime of the permissible transmission period; and transmitting the logdata to the collection device at the determined timing.
 10. Anon-transitory computer-readable medium storing a program causing acomputer to perform: transmission determination processing ofdetermining a timing of transmitting log data, within a permissibletransmission period, being a time span in which transmission of the logdata, accumulated locally, is permitted, based on an own state, a stateof a network, and a remaining time of the permissible transmissionperiod; and transmission processing of transmitting the log data to acollection device connected through the network, at the determinedtiming.